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Author Topic: Getting too much bass in sound. Bernie Anderson Jr Master Film Handler Posts: 435 From: Woodbridge, New Jersey Registered: Apr 2000 posted 01-04-2002 10:39 PM                        Here's something that I've been trying to figure out since I got my machine running. Here's the deal. I'm running a mono sound system with a Kelmar amp and a RCA 9050 My speakers are older AR Hi-fi speakers and the slit lens I believe is 1 mil And the A-chain was aligned. Now, what would be the cause of having too much bass and an okay amount of mid to high end and how can it be fixed? Would a .5mil slit do it? or is it just the speakers? If it is the speakers, what kind of speakers should I be using. And I don't have the space for any kind of professional theatre speakers. What kind of speakers do you guys have at home? Thanks Bernie  |  IP: Logged John Walsh Film God Posts: 2490 From: Connecticut, USA, Earth, Milky Way Registered: Oct 1999 posted 01-04-2002 11:22 PM                     Need more details. What processor are you using? Making the slit size larger will increase the output, but decrease the hi freq, so I don't think that's the problem. I don't think it's a 1 mil slit; that's pretty small. Are you saying the A-chain aligned correctly, but the B-chain isn't? You could test the speakers by hooking them up to a regular tuner/amplifier and listening. Most films have a Dolby optical track; not decoding them will result in strange sound.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-04-2002 11:44 PM                     Bernie, I'm assumming that this is a small screening room situation.... The AR speakers, if they are behind a perforated screen will never suffice. The AR's were never known for lots of high end in the first place and a perforated screen will only serve to attenuate the high end even more. Pushing them with an EQ would probably only result in the destruction of the tweeters and possibly parts in the X-over. I used to repair AR speakers at a Hi-Fi service center that I worked at when I got out of High School. A theatre type speaker is in order for you in this case. A small JBL would work out nicely and won't set you back a ton of $$ either. Also watch E-Bay for used Dolby CP-50 processors. They can be had for a cheaply as 150.00 and having one will allow you to set up a proper optical playback chain. This is the first pre-requisite........ It is possible, and very common with older RCA slit lenses to fill with oil. If this is the original lens it probably does have at least some oil in it and can give you a somewhat muffled playback. Even with an inexpensive spectrum analyzer and loop of pink noise this problem will show up quite readily, and you won't be able to get decent response no matter how you try to adjust the slit lens focus. If this is the case a .5 mil slit lens is in order for you, especially if you were to get a proper processor. It is not a bad idea to do an upgrade anyway and can't hurt. A reverse scan LED retrofit is even better, and far more stable, but more costly. Please provide us some more details and we'll see if we can be of more help to you. Mark @ GTS  |  IP: Logged John Anastasio Master Film Handler Posts: 325 From: Trenton, NJ, USA Registered: Sep 2000 posted 01-05-2002 09:41 AM                        If you want to try a different lens, you're welcome to the 1 mil I removed from my 9050 down here in Trenton. I'd pop for the .5 marble myself...the difference is audible and if you want to do surround stereo, you'll need one anyway to do it right. You can get them from any supplier.  |  IP: Logged Patrick de Groot Expert Film Handler Posts: 161 From: Sprang-Capelle, Netherlands Registered: Apr 2001 posted 01-05-2002 12:55 PM                     If you're using a mixer make sure you're using microphone preamplifiers! Using the phono input will result in the problem you describe: high bass en low treble. This has something to do with the frequency curve of a pick-up. Also it is a good idea to put an equalizer in between so you can fine tune the sound. Next is the use of some dolby surround decoder for home use. Of course you have to have a stereo solarcell for this to work. You can make some really nice sound using this kind of equipment!  |  IP: Logged John Anastasio Master Film Handler Posts: 325 From: Trenton, NJ, USA Registered: Sep 2000 posted 01-05-2002 01:27 PM                        Does your cell connect directly to the Kelmar? I'm assuming it already has a preamp built in. If not, and your'e using a preamp.....he's right. You'll get a REALLY bassy sound from using a magnetic phono input, since they're equalized to an RIAA curve, which really boosts the bass to counteract the rolloff used in the cutting process.  |  IP: Logged Bernie Anderson Jr Master Film Handler Posts: 435 From: Woodbridge, New Jersey Registered: Apr 2000 posted 01-05-2002 03:47 PM                        More Info: Mono Kelmar solar cell directly into a Kelmar amp (preamp and amp all in one models-the little blue ones) Comes out of the amp into the speakers. There is no stereo cell, dolby processors or equalizers. thanks Bernie  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 01-06-2002 07:03 PM                     Bernie, in addition to the above suggestions, make sure your solar cell is properly loaded and decoupled. Also make sure your sound focus is correct. If you used the sound focus tracks of test film (including pink noise) and the test strip was in backwards, your high end will suffer. (emulsion towards the rear....)  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 01-06-2002 09:01 PM                     The cell loading is part of the Kelmar basically the slit wisth limits the hi end response but a narrower slit will reduce the gain Is by chance you Kelmar one of the ones with the twin proj balancing pot  |  IP: Logged Bernie Anderson Jr Master Film Handler Posts: 435 From: Woodbridge, New Jersey Registered: Apr 2000 posted 01-07-2002 08:31 AM                        No, the amp is one projector input only. I have both cells hooked up to the terminals and I'm switching between the projectors via the exciter lamp  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 01-07-2002 10:20 AM                     The second cell is loading the first one down. There is a set of decoupling resistors and pot that kelmar supplies on a little board and terminal strip for 2 machine operation  |  IP: Logged

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